The search of Donald Trump's Mar-a-Lago home is said to have been prompted by an ongoing investigation into the boxfuls of documents the former president brought to Florida after leaving the White House, including notes from North Korean leader Kim Jong Un and even a cocktail napkin.

There were around three pages of an inventory list of classified materials, but there were no apparent indications of what the information was. Schedules, a phone list, letters, memos, talking points, Slideshow decks, and schedules were also included.

When the National Archives claimed to have collected 15 boxes of White House records from Mar-a-Lago, including secret information, a dispute over the materials first broke out. Trump was supposed to have turned over the records when he left office.

On Monday, the Feds removed 12 more boxes of material. According to sources, The Wall Street Journal was informed that among the papers found in January were letters from Barack Obama to his successor and correspondence from Kim Jong Un.

Also, a list of the unclassified materials discovered in the boxes was around 100 pages long and included the cocktail napkin and a birthday dinner menu, The Washington post said.

The revelation from the National Archives, which is in charge of collecting presidential material, sparked a months-long Justice Department investigation into whether Trump was illegally storing classified information at his private club and estate.

Investigators reportedly paid a visit to Mar-a-Lago in early June to speak with Trump's lawyers about handing over more potentially classified information. During that visit, Trump briefly came by to greet the federal agents before they were led to a basement room where the documents were kept, according to the sources.

Then the FBI asked Trump's attorneys to secure the room where the documents were five days later. After sources told Fox News that investigators were not getting the same level of cooperation from Trump's side as before, the FBI sought a search warrant for Monday's raid.

Investigators think there may possibly be more secret documents on Trump's property.

It is unknown what the feds seized during the latest search warrant, which occurred while Trump was at his Manhattan residence. According to the Washington Post, the FBI removed about a dozen boxes from a locked basement storage area on Monday.

No comments on the raid have been made by the Justice Department.

Trump criticized the raid as "not necessary" and said he had been complying with the authorities, but the former president has still not made the warrant's specifics public.